Paint spray machine



March 19,1963 w. A. BRADY, JR 3,081,736

PAINT SPRAY MACHINE Filed Feb. 24, 1961 4 Sheets-Sheet 1 INVENTOR WILLIAM A. BRADY JR.

BY M 9 W ATTORNEY March 19, 1963 w. A. BRADY, JR

PAINT SPRAY MACHINE 4 Sheets-Sheet 2 Filed Feb. 24, 1961 m m m 8 I 4 w 0 o m 6 m I! l| 4 rw MHVFVIHIIIHIIIIIJIHIIIll A- FEEEF L A n 3 -J. l w w .3 ii, IIII .13 1 m4 m r\||||. L F FFF L 3 4 I L 2 Q m 2 i I I 1%-- WILLIAM A.BRADY JR.

ATTORNEY March 19, 1963 w. A. BRADY, JR

PAINT SPRAY MACHI m m M Filed Feb. 24, 1961 ATTORNEY March 19, 1963 w. A. BRADY, JR 3,081,736

PAINT SPRAY MACHINE Filed Feb. 24, 1961 4 Sheets-Sheet 4 I INVENTOR Y WILLIAM A. BRADY JR.

ATTORNEY United States Patent Office 3 ,081,736 Patented Mar. 19, 1963 3,081,736 PAINT SPRAY MACHINE William A. Brady, Jr., Warren, Mich, assignor to General Motors Corporation, Detroit, Micln, a corporation of Delaware Filed Feb. 24, 1961, Ser. No. 91,493 9 Claims. (Cl. 118-323) This invention relates to an automatic spraying machine and more particularly to a linkage arrangement for permitting a spray device to maintain a substantially uniform velocity as it tran-scribes a curved surface.

To facilitate the mass production of automobile bodies, the latter are often mounted on a carrier which in turn is fixed to a continuous-1y traveling conveyor system. At a predetermined point in the body travel, the outer shell of each body is spray coated by one or more spraying devices carried by an automatic spraying machine. Generally, the driving mechanism of the spray device follows a linear path, and where the outer shell of the automobile body is curved, the spray device travels on a curved guide track having a configuration that conforms to that of the body surface. This arrangement results in the spray device covering a distance greater than the associated driving mechanism. When this occurs, the spray device tends to accelerate or decelerate during certain portions of the curve, and depending upon the nature of the curvature. This irregular travel of the spray device produces a build up or deficiency of coating material on the body surface resulting in a touch-up station being required or the entire body being rejected because of runs or tears which could occur when an excess amount of coating material is deposited on a surface.

In the past, where the surface to be coated was of a curved configuration, appropriate mechanism was incorporated with the spraying machine to compensate for any variable velocity of the spray device so that a uniform thickness of the coating material would be deposited on the body surface. For example, in some machines the discharge flow of the coating material from the spray device would be controlled to prevent a build-up or deficiency of coating material on a curved surface. In other machines, the velocity of the spray device as it traverses a curved surface would be decreased or increased so as to obtain a uniform thickness of coating material on the body surface. In each instance, the apparatus required to either control the paint flow or spray device speed has rendered the automatic spray machine quite complicated and undependable in providing a uniform thickness of paint on the surface to be coated.

The present invention is directed towards alleviating the complex control apparatus heretofore required in automatic spraying machines for obtaining a uniform coating, and substituting therefore a simple mechanical linkage that is capable of providing the spray device with a substantially uniform velocity as the latter traverses a curved surface. Stated broadly, this is accomplished by a toggle arm arrangement which is interposed between a main and a secondary carriage. The main carriage is adapted to be reciprocably driven alon an elongated controlshaft, while the secondary carriage is movably mounted on a curved guide track. A spray device is attached to the secondary carriage and is maintained normal to both the guide track and the surface to be coated by a plurality of followers rotatably secured to the secondary carriage. The toggle arm arrangement comprises two sets of toggle arms which are interconnected by gear means for controlling the position of the spray device during its travel along the curved guide track.

An object of the present invention is to provide an automatic spraying machine having mechanical control means for obtaining a uniform thickness of coating material on a curved surface.

Another object of the present invention is to provide an automatic spraying machine in which a spray device traverses a curved surface at a substantially uniform velocity and is maintained normal to the surface being coated.

Still another object of this invention is to provide an automatic spraying machine incorporating mechanical control means to permit the spray device to traverse a curved surface at a substantially uniform velocity and maintain the latter normal to the surface being coated.

A further object of thisinvention is to provide an automatic spraying machine employing a mechanical linkage arrangement that controls the movement of a spray device on a concave guide track and permits the spray device to travel a linear distance greater than that covered by the main driving carriage.

Other objects and advantages of the invention will'be apparent from the description which follows: and from the accompanying drawings in which:

FIGURE 1 illustrates an elevation view of an automatic spraying machine incorporating the present invention.

FIGURE 2 is a rear view of the automatic spraying machine of FIGURE 1.

FIGURE 3 is an enlarged view of the present invention taken on lines 3-3 of FIGURE 2.

FIGURE 4- is another enlarged view of the present invention taken on lines 4-4 of FIGURE 2.

FIGURE 5 is a schematic drawing of the subject invention disclosing the primary and secondary carriages and the relative positions of the link members when the present invention is utilized for coating a convex surface.

Referring to FIGURES 1 and 2, an automatic spray machine generally indicated by the numeral 10 is shown disposed adjacent an automobile body 12. The body 12 is shown in cross section with a portion thereof curved outwardly towards the machine 10. The body 12 is mounted on a conveyor carrier which is not shown and which is movable thereby towards the observer to present the entire outer curved shell of the body to a flow of atomized coating material emanating from the automatic spray machine 10. More specifically, the automatic spraying machine 10 comprises an electric motor 14 that is secured to a base 36 and is drivingly connected to a gear 16 by a link chain 18. The gear 16 is mounted on a shaft 22 that includes a sprocket 20. The shaft 22. is disposed with its longitudinal axis perpendicular to the path of travel of the chain 18 and is rotatably mounted in a lower supporting housing 24. Similarly, a follower sprocket 26 is rotatably mounted on a shaft 28 which in turn is journaled in an upper support housing 30. The opposite end of the shaft 28 is associated with a pulley arrangement that drives a timing mechanism which forms no part of this invention. The follower sprocket 26 cooperates with the sprocket 20 to drive a drive link chain 32. An elongated control shaft 34 is vertically mounted in the machine 10 with its lower and upper ends respectively secured in the base 36 and in a support bracket 38. A carriage assembly generally indicated by the numeral 40* includes four guide rollers 42 rotatably mounted thereon with a portion of peripheral surfaces thereof embracingly engaging the control shaft 34. The guide rollers 42 are arranged in sets of two located at the extreme vertical ends of the assembly to provide for stalggity of the latter during its travel on the control shaft The carriage assembly 40 consists of a primary or main carriage 44 and a secondary carriage 46. The secondary carriage 46 is connected to the primary carriage 44 by a pair of toggle arm arrangements which will be described hereinafter in more detail. A spray device 48 is connected to the secondary carriage by extension members 50 and 52. A curved guide bar 54 is mounted in the machine 10 and secured to the brackets 56 and 58 disposed in the upper and base portions of the machine, respectively. A plate 60' is attached to the framework of the spray machine and serves to cover the above described mechanism to protect the same from the atomized coating material emanating from the spray device 48. An arcuate slot 62 is cut in the plate 60 to permit the spray device 48 to be disposed laterally of the spray machine as best viewed in FIGURE 2.

Referring now to FIGURES 3 and 4, a more detailed drawing is shown of the carriage assembly and linkage arrangement which constitutes the invention. Referring first to FIGURE 3, it can be seen that the primary carriage 44 has a rectangular guide block 64 secured thereto. The guide block 64 is formed with a guide channel 66 and is mounted on the primary carriage 44 so as to locate the longitudinal axis of the guide channel normal to the control shaft 34. A circular roller 68 is fixed to the master link of the drive chain 32 and is slidably disposed within the guide channel 66. This arrangement joins the drive chain 32 to the carriage assembly 40 and permits reciprocal movement of the latter during the oval travel of the drive chain.

The secondary carriage 46 includes a pair of spring loaded rollers 72 which are rotatably mounted on a pivoted support bar 74. The rollers 72 cooperate to maintain the secondary carriage in engagement with the curved guide track 54 and permit the secondary carriage to follow the same during the vertical travel of the primary carriage 44. As aforementioned, the primary carriage 44 and the secondary carriage 46 are connected together by a toggle arm arrangement. The toggle arm arrangement comprises two sets of toggle arms, each of which has a control link 76 and a pair of stabilizer links 78. As best seen in FIGURE 2, the control link 76 is in the form of a T with its cross member pivotally joining the two links 78 at a point 80. The other end of each stabilizer link 78 is pivotally connected to the secondary carriage 46 at a point 82. On the other hand, the opposite end of the control link 76 is embedded within a segment gear 84 which is pivotally mounted to the primary carriage 44. At this point it should be understood that a similar link set is symmetrically disposed below the longitudinal axis ofthe guide channel 66. The teeth 86 of the segment gears 84 are operatively engaged andserve to interconnect the toggle link sets to provide for the controlled movement of the secondary carriage 46.

The operation of the subject invention is as follows. When the electric motor 14 is energized, the connecting link chain 18 rotatably drives the gear 16 which as' aforementioned is connected to the driving sprocket 20 through the shaft 22. The driving sprocket 20 and the follower sprocket 26 cooperate to drive the drive chain 32 which is connected through the roller and block arrangement to the primary carriage 44. As aforedescribed, the roller and 'block arrangement permits the oval movement of the drive chain 3-2 to be translated into a reciprocal movement of the primary carriage 44 on the control shaft 34. As the primary carriage 44 moves in an upward or downward direction, the secondary carriage 46 is apt to follow the guide track 48 onto which. it is mounted. As the primary carriage 44 is moved in an upward direction from line X X to line X X as viewed in FIGURE 5, the control links 76, due to the interconnecting segment gears 84, assume positions of equal distance from the vertical center line Y,Y. In eontradistinction, the stabilizer links 78 are forced to follow the movement of the secondary carriage 46 so as to dispose the stabilizer links at unequal angles with respect to the control links. However, as can readily be seen, the toggle link arrangement permits the axis which is normal to the longitudinal axis of the secondary carriage 46 to intersect the center axis of the primary carriage located on the line X X at a point A on the surface to be sprayed or closely adjacent thereto. It is possible with the. toggle arm arrangement to achieve the above relationship throughout the elfective spray range. A movement of the primary carriage 44 and the associated secondary carriage in a downward position to the position defined by the line X X provides a symmetrically similar arrangement of the link members as when the primary carriage moves in an upward direction.

Since the point of intersection A of the center line of the primary carriage 44 and the center line normal to the longitudinal axis of the secondary carriage is on the surface to be coated or closely adjacent thereto, it can be readily seen from FIGURE 5 that this point A travels at a vertical velocity equal to that of the primary carriage. The vertical velocity of the point A, therefore, is the same as that of the drive carriage. However, as this point transcribes an arc, it travels a greater distance than that of the drive carriage in a given length of time and as such must necessarily attain a higher velocity. As shown in FIGURE 5, the greatest percentage change in the length of arc compared to the corresponding vertical travel of the drive carriage is 6 As velocity is the product of distance and time, it follows that the maximum variation in velocity over this curve would also be 6%. This occurs at each end of the stroke.

To obtain the advantages of the subject linkage arrangement, the spray device 48 is positioned so that the longitudinal axis thereof is in alignment with the center line of the secondary carriage 46. In this manner the spray being emitted from the spray device 48 impinges on the body surface as a projection of the horizontal center line of the primary carriage 44. An additional advantage is provided by the subject toggle arrangement in that the vertical extent of travel of the secondary carirage 46 is of a greater length than the vertical travel of the primary carriage 44. This can best be seen in FIGURE 5. The toggle arrangement assures that the surface located between extreme upper and lower points of travel of the primary carriage 44 will be coated, and permits a utilization of a drive train in which the drive sprocket and follower sprocket are disposed a distance equal to or less than the distance between the extreme points of paint impingement on the surface being coated.

It should be understood that although I have described my invention in some detail, modifications and variations may be made in the form and arrangement of parts without departing from the spirit of my invention. I do not therefore wish to be limited to the exact structure herein shown and described but as my invention all forms thereof coming within the scope of the appended claims.

What is claimed is:

1. In a spraying mechanism for coating a curved surface, a control shaft, a main carriage movable along said control shaft, means including a power source for reciprocably driving said main carriage, a guide track of a configuration conforming to said surface, a secondary carriage mounted to said guide track to ride thereon, said secondary carriage having a spray device attached thereto and movable therewith for maintaining the spray emitted from said spray device normal to said guide track and said surface, connecting means interposed between said main and secondary carriage, said connecting means comprising link members pivotally connected to said main and secondary carriage, and means operatively associated with said link member for controlling the position of said spray device whereby the axis of the spray emitted from the spray device and a center line through said main carriage normal to the path of travel of the latter intersect at a point adjacent to said surface during the entire travel of the secondary carriage on the guide track.

2. In a spraying mechanism for coatnig a curved surface, a control shaft, a main carriage movable along said control shaft, means including a power source for reciprocably driving said main carriage, a guide track of a configuration conforming to said surfaces, a secondary carriage having means engaging said guide track to ride thereon, said secondary carriage having a spray device attached thereto and movable therewith for maintaining the spray emitted from said spray device normal to said guide track and said surface, connecting means interposed between said main and secondary carriage, said connecting means comprising stabilizer links pivotally connected to said secondary carriage, coated links pivotally connected to said main carriage, said stabilizer and control links pivotally joined together at the free ends thereof for controlling the position of said spray device whereby the axis of the spray emitted from the spray device and a center line through said main carriage normal to the path of travel of the latter intersect at a point on said surface during the entire travel of the secondary carriage on the guide track.

3. In a spraying mechanism for coating a curved surface, a control shaft, a carriage movable along said control shaft, means including a power source for reciprocably driving said carriage, a guide track of a configuration conforming to said surface, a spray assembly including follower means for riding on said guide track and for maintaining the spray emitted from said spray assembly normal to said guide track and said surface, connecting means interposed between said carriage and said spray assembly, said connecting means comprising a pair of stabilizer links pivotally connected to said spray assembly, a pair of control links pivotally connected to said carriage, each of said stabilizer and control links pivotally joined together at the free ends thereof, and means including said control links for controlling the position of said spray assembly whereby the axis of the spray emitted therefrom and a center line through said carriage normal to the path of travel of the latter intersect at a point adjacent to said curved surface.

4. In a spraying mechanism for coating a curved surface, a control shaft, a main carriage movable along said control shaft, means including a power source for reciprocably driving said main carriage, a guide track of a configuration to conform to said surface, a secondary carriage including follower means for riding on said guide track, said secondary carriage having a spray device attached thereto and movable therewith for maintaining the spray emitted from said spray device normal to said guide track and said surface, connecting means interposed between said main and secondary carriage, said connecting means comprising a pair of stabilizer links pivotally connected to said secondary carriage, a pair of control links pivotally connected to said main carriage, each of said stabilizer and control links pivotally joined together at the free end thereof, and means including said control links for controlling the position of said spray device whereby the axis of the spray emitted from the spray device and a center line through said main carriage normal to the path of travel of the latter intersect at a point adjacent to said surface.

5. In a spraying mechanism for coating a curved surface, a control shaft, a main carriage movable along said control shaft, means including a power source for reciprocably driving said main carriage, a guide trackof a configuration to conform to said surface, a secondary carriage including follower means for riding on said guide track, said secondary carriage having a spray device attached thereto and movable therewith for maintaining the spray emitted from said spray device normal to said guide track and said surface, connecting means interposed between said main and secondary carriage, said connecting means comprising a pair of stabilizer links pivotally connected to said secondary carriage, a pair of control links pivotally connected to said main carriage, each of said stabilizer and control links pivotally joined together at the free ends thereof, a segment gear connected to each of said control links, said segment gears operatively engaging each other for controlling the position of said spray device whereby the axis of the spray emitted from the spray device and a center line through said main carriage normal to the path of travel of the latter intersect at a point on said surface.

6. In a spraying mechanism for coating a curved surface, a control shaft, a carriage movable along said control shaft, means including a power source for reciprocably driving said carriage, a guide track of a configuration conforming to said curved surface, a spray assembly including means for riding on said guide track and for maintaining the spray emitted from said spray assembly normal to said guide track and said curved surface, connecting means interposed between said carriage and said spray assembly, said connecting means comprising a pair of stabilizer links pivotally connected to said spray assembly, a pair of control links pivotally connected to said carriage, each of said stabilizer and control links pivotally joined together at the free ends thereof, a segment gear connected to each of said control links, said segment gears operatively engaging each other for controlling the position of said spray device whereby the axis of the spray emitted from the spray device and a center line through said carriage normal to the path of travel of the latter intersect at a point on said curved surface.

7. In a spraying mechanism for coating a curved surface, a control shaft, a carriage movable along said control shaft, means including a power source .for reciprocaly driving said carriage, a guide track of 1a configuration conforming to said surface, a spray assembly including follower means for riding on said guide track and for maintaining the spray emitted from said spray assembly normal to said guide track and said surface, connecting means interposed between said carriage and said spray assembly, said connecting means comprising a pair of stabilizer links pivotally connected to said spray assembly, a pair of control links pivotally connected to the free ends of said stabilizer links and pivotally mounted on said carriage, means formed with said control links so as to provide conjoint operation of the latter, said means permitting said control links to assume equal angular distances from a center line passing through the carriage pivot points of said control links whereby said spray assembly maintains substantially uniform velocity during its travel along said curved guide track.

8. In a spraying mechanism for cotaing a curved surface, a control shaft, a main carriage movable along said control shaft, means including a power source for reciprocably driving said main carriage, a guide track of a configuration to conform to said surface, a secondary carriage including follower means for riding on said guide track, said secondary carriage having a spray device attached thereto and movable therewith for maintaining the spray emitted from said spray device normal to said glide track and said surface, connecting means interposed between said main and secondary carriage, said connecting means comprising a pair of stabilizer links pivotally connected to the secondary carriage a pair of control links pivotally joined to the free ends of said stabilizer links and including first means for pivot-ally mounting said control links on said main carriage, second means formed on said first means :so as to provide conjoint operation of said second links, said second means permitting said second links to assume equal angular distances from a center line passing through the pivot points of said first means whereby said spray device maintains substantially uniform velocity during its travel along said curved guide track.

9. In a spraying mechanism for coating a curved surface, a control shaft, 21 main carriage movable along said control shaft, means including a power source for reciprocably driving said main carriage, a guide track of a confiuraticn conforming to said surface, a secondary carriage for riding on said guide track, said secondary carriage having a spray device attached thereto and movable therewith for maintaining the spray emitted from said spray device normal to said guide track and said surface connecting means interposed between said main and secondary carriages, said connecting means comprising a pair of stabilizer links pivotally connected to said secondary carriage, :a pair of control links pivotally joined to the free ends of said stabilizer links and including 21 segment :gear for pivotally mounting each of said control links on [said main carriage, said segment gears operatively engaging each other to pnovide conjoint operation of said control link-s whereby the latter assume equal angular 10 distances from a center line passing through the pivot points of said gears so that said spray device maintains a substantially uniform velocity during its travel along said curved guide track.

References Cited in the file of this patent UNITED STATES PATENTS 2,083,633 Brackett June 15, 1937 

1. IN A SPRAYING MECHANISM FOR COATING A CURVED SURFACE, A CONTROL SHAFT, A MAIN CARRIAGE MOVABLE ALONG SAID CONTROL SHAFT, MEANS INCLUDING A POWER SOURCE FOR RECIPROCABLY DRIVING SAID MAIN CARRIAGE, A GUIDE TRACK OF A CONFIGURATION CONFORMING TO SAID SURFACE, A SECONDARY CARRIAGE MOUNTED TO SAID GUIDE TRACK TO RIDE THEREON, SAID SECONDARY CARRIAGE HAVING A SPRAY DEVICE ATTACHED THERETO AND MOVABLE THEREWITH FOR MAINTAINING THE SPRAY EMITTED FROM SAID SPRAY DEVICE NORMAL TO SAID GUIDE TRACK AND SAID SURFACE, CONNECTING MEANS INTERPOSED BETWEEN SAID MAIN AND SECONDARY CARRIAGE, SAID CONNECTING MEANS COMPRISING LINK MEMBERS PIVOTALLY CONNECTED TO SAID MAIN AND SECONDARY CARRIAGE, AND MEANS OPERATIVELY ASSOCIATED WITH SAID LINK MEMBER FOR CONTROLLING THE POSITION OF SAID SPRAY DEVICE WHEREBY THE AXIS OF THE SPRAY EMITTED FROM THE SPRAY DEVICE AND A CENTER LINE THROUGH SAID MAIN CARRIAGE NORMAL TO THE PATH OF TRAVEL OF THE LATTER INTERSECT AT A POINT ADJACENT TO SAID SURFACE DURING THE ENTIRE TRAVEL OF THE SECONDARY CARRIAGE ON THE GUIDE TRACK. 